Objective: To determine the information needed by patients in relation to the supply of primary care services from the perspective of health professionals. Methods: The Delphi technique was used as a consensus method. Seventy experts were asked to participate: 35 primary care physicians, 32 nurse practitioners, and three pediatricians in rural and non-rural health centers in the Health Area of Salamanca between May and December 2006. The questionnaires used were structured into six sections: patients' knowledge of their health, services in their health centers, administrative topics, the media, information expectations, and communication barriers. In the third questionnaire, prioritized answers were scored between 5 points and 1 point according to their importance. Results: All three questionnaires were completed by 44 experts (62.8%). The information needs with the highest scores were information on patients' diseases (4.0 points), subjects related to patients' responsibility for their health (3.8) and preventive advice (3.6), followed by subjects relating to access (4.2), emergencies (3.4), physicians' and nurse practitioners' services (3.6), and places to go to get information (4.0). The lack of coordination between primary and hospital care (4.1) and excessive bureaucracy (3.5) were considered to limit communication and information. Conclusions: The factors identified focus on contents that allow patients to get involved in their own process and to take active part in the decision-making that concerns them. Other important factors were information about services and the access to them.